BERLIN - Voting began on Sunday in Germany's northern state of Schleswig-Holstein, where Angela Merkel's conservatives are neck-and-neck with their Social Democrat rivals and know a loss of control of the state could dent the chancellor's 2013 re-election hopes.

Merkel's resolute stance through the dramas of the euro zone crisis has left her personal popularity intact. But her national center-right coalition is in jeopardy after a slump in public support for her junior coalition partners, the Free Democrats (FDP), due to their infighting and prickly leaders.

To have any chance of fulfilling her hopes for a third-term in power, she must find new allies for her Christian Democrats (CDU) and hope a dismal run at regional level for both her party and the FDP is at an end.